The invention relates to insulated board and in particular to a method for manufacturing a foam panel.
In conventional reactive foam panel manufacture a first facing is delivered to an area at which liquid foam reactants are delivered onto the first facing. A second facing is led over the liquid foam reactants. The foam is then heated and allowed to rise to a predetermined height.
Such manufacturing processes are widely used and are generally successful. There is however an increasing need to maintain competitiveness by reducing manufacturing costs whilst producing a high quality board.
This invention is therefore directed towards producing an improved manufacturing process of this type.
According to the invention there is provided a method for manufacturing a foam panel comprising the steps of:
leading a first facing from a first facing supply to a foam lay down area;
laying liquid foam reactants on the first facing;
leading a second facing from a second facing supply over the liquid foam reactants;
allowing the foam to expand between the facings to form a foam panel;
removing at least one of the facings from the foam; and
applying a coating to one or both faces of the foam from which the facings have been removed.
Most preferably the coating is applied in-line. The coating is preferably in a liquid form. Preferably the coating is a paint. In one case the paint contains non-gas permeable flake-like particles or platelets such as metal or glass flakes. The paint may contain aluminium flakes.
In a preferred embodiment the paint contains nanocomposites.
In one embodiment the coating is applied by a calendering roll.
Alternatively or additionally the coating is applied by passing the panel with the facings removed through a curtain of the coating material.
Alternatively or additionally the coating is applied by spray coating.
Alternatively the coating is applied electrostatically.
In a particularly preferred embodiment of the invention the method includes the step, after applying the coating, of curing the coating on the foam. Preferably the curing is carried out in-line.
Most preferably, the coating is cured by heating and/or by application of radiation.
The coating may be cured by localised application of heat and/or radiation.
In one arrangement the method includes the step after coating, of passing the coated panels through an accumulator.
The method may include the step, before or after coating, of turning the panel to lie on an edge thereof.
Ideally the method includes the step, after coating, of cutting the panel to a desired length.
Preferably the method includes the step, after at least partial curing of the coating, of cutting the panel to a desired length.
The paint may be a leafing or non-leafing paint.
Ideally the coating is of low gas permeability, especially to CO2, O2, N2 and/or H2O.
In one embodiment of the invention both facings are removed from the foam for re-use.
In a preferred arrangement one or both facings is/are peeled from the foam and coiled onto a take-off reel for re-use either as the first or second facing supply.
Typically the upper facing is coiled onto an upper facing recycle coil to provide a facing supply for the second facing. Preferably the upper facing recycle coil is delivered to a second facing feeding station. Preferably the lower facing is coiled onto a lower facing recycle coil to provide a facing supply for the first facing. Typically the lower facing recycle coil is delivered to a first facing feed station.
In a preferred embodiment of the invention the first and/or second facings are removed from the foam core after at least partial curing of the foam core.
Ideally, the first and/or second facings are removed from the core in advance of cutting of the foam to a desired length.
In one arrangement release means is provided between the inner face of the first and/or second facing and the foam core. Typically the release means is provided on the inner face of the first and/or second facing.
In one embodiment of the invention the first and/or second facing is selected from:
polyolefin films (such as polypropylene, high or medium density polyethylene, low or linear low density polyethylene), poly halogenated polyolefins (such as polytetrafluoro ethylene), waxed paper and waxed plastic films, other suitably treated paper, plastic, metal foil or glass films and facings and combinations thereof such that the facing can be continuously removed from the foam without significant damage to either facing or foam during or just following the production process.
The foam is preferably selected from polyurethane, polyisocyanurate and phenolic.
Preferably the foam has significant cellular structure for use in thermal and/or acoustic insulation applications.
The invention further provides a foam panel whenever manufactured by a method of the invention. The panel is free from a facing on one or both faces thereof. At least one of the faces of the panel is coated with a coating material, preferably a paint.
The invention also provides a foam panel comprising a foam core having a first face and a second face, at least one of the faces having a coating applied thereto. Preferably the coating is a paint. Most preferably the foam core is of polyurethane, polyisocyanurate or phenolic material.
The panel may for example, be used as an underfloor insulation panel. Alternatively the panel may be an insulation liner panel, for example for use in refrigeration applications such as for a refrigerated transport vehicle.